Documentation

juxtapose v a1 a2 positions a2 next to a1 in the
direction of v. In particular, place a2 so that v points
from the local origin of a1 towards the old local origin of
a2; a1's local origin becomes a2's new local origin. The
result is just a translated version of a2. (In particular,
this operation does not combinea1 and a2 in any way.)